1. Field of the Invention
The present invention concerns a clutch, in particular for automobile vehicles, comprising at least one friction disk and clutch plates for clamping this friction disk, at least one of these clutch plates being operated on by, on the one hand, elastic clutch engagement means which urge the clutch plates together to clamp the friction disk and thereby engage the clutch and, on the other hand, clutch release control means comprising a pedal and adapted to move the clutch plates apart to unclamp the friction disk and thereby release the clutch, and assistance means for reinforcing the action of the pedal.
2. Description of the Prior Art
These assistance means are not intended to eliminate all the effort which the driver has to exert on the pedal, but merely to reduce this effort. In this way the driver remains highly sensitive to vehicle driving conditions without excessive fatigue. Assistance of this kind is of particular but not exclusive benefit in the case of heavy goods vehicles. In such vehicles, when there is no assistance, it is often necessary to provide two friction disks to obtain a reasonable pedal operating force, which complicates construction.
Since this kind of assistance entails a residual force to be exerted on the pedal by the driver, the intervention of the assistance means must be perfectly harmonised with the action of the driver on the pedal, given that the resistance of the elastic clutch engagement means varies with travel. It is often considered desirable to vary the assistance force proportionately to variations in the resistance due to the elastic clutch engagement means. The curve of these variations may have a more or less simple shape according to the nature of the elastic clutch engagement means. This shape is relatively simple when these elastic means consist in helical springs. It is slightly more complicated, featuring a saddle, when the elastic clutch engagement means consist in a diaphragm spring.
Assistance means as proposed until now have not provided a totally satisfactory respose to this condition and have not provided for a convenient choice in the manner of variation in the assistance force, not only to take account of variations in the resistance of the elastic clutch engagement means, but also and more generally to obtain operating conditions which are optimised from all points of view.
An object of the present invention is a clutch, in particular for automobile vehicles, of the type indicated hereinabove and which constitutes a better response than available in the past to the various desiderata of good practice and the assistance means of which, for reinforcing the action of the pedal, meet the most severe and the most diverse demands to secure faultless operation.